One problem in the field of orthopedic implants and in particular of spinal implants relates to arthrodesis, i.e. the fusion of two bone structures, which is often desirable or necessary to accomplish to treat a patient. The success of this type of treatment depends in general on the speed and/or the reliability of the bone fusion obtained. This speed and this reliability are often linked, and are often based on the quality of the immobilization of the two bone structures that it is desired to fuse. Thus, a second problem in the field relates to the attachment of bone implants and in particular the reliability of that attachment. Moreover, in the particular case of the spine, these problems are accompanied by various problems and constraints connected with crowding around the sites to be treated. In fact, obtaining fusion of at least two vertebrae is sometimes attempted, for example when at least one of their adjacent inter-vertebral disks is damaged. Known from the prior art are various arthrodesis techniques, based on various types of implants, such as intersomatic (or arthrodesis) cages for example, inserted in place of a disk to promote bone growth, or the corpectomy cages which replace a vertebral segment sometimes containing at least a portion of at least one vertebral body, generally in addition to at least one intervertebral disk. Also known, particularly at the lumbar or sacral level, are solutions using facet implants (inter-facet or trans-facet) allowing attachment of the articular facets of two vertebrae for the purpose of obtaining fusion between them. Generally, these various solutions aim to resolve, in addition, the problem of the stability of the implant and of the vertebral structures treated. It is necessary that an implant be stable in its implantation site, in particular when an arthrodesis is desired because the latter must take place in a relative position of the elements of the spine which is optimal (as desired by the surgeon). Stabilization and/or locking of the implant is (are) therefore preferable.
These solutions have the disadvantages of not always responding correctly to the general problems of facility and/or speed of implantation and of the invasiveness of the implants and of the surgical techniques which depend on them. In fact, it is generally desired that the implants be able to be implanted quickly and/or easily, with minimal invasiveness, i.e. it is desired to limit the size of the incisions and of the damage to the surrounding tissue. This problem of invasiveness relates in particular to the introduction of implants into the spine and particularly to access to the intervertebral spaces (disc spaces) which is often particularly delicate due to crowding, due for example to the presence of blood vessels and of nerves around the intervertebral space, as well as the proximity of the spinal cord.
Finally, another problem in the field of implants relates to the variability of individuals and pathologies. For example, the size of vertebrae is highly variable depending on the individuals and depending on the position in the spinal column, but the great variability of disorders and pathologies of the patients makes the design of implants even more complex. To have available usable implants to respond to the needs of a greater number of patients, it is necessary to provide a large number of implants which differ in size and/or in the inclination of their bone contact surfaces and/or in their bone anchoring, etc. This multiplicity of necessary implants presents a major disadvantage in cost of production and in stock management. Moreover, a problem which is derived implicitly from those mentioned above relates to the fact that it is sometimes useful to supply a system of implants (particularly for arthrodesis) the bone anchoring whereof can vary depending on needs, or even be decided at the last moment, i.e. just before the implantation of the system into the patient, or even actually during the implantation. In fact, the surgeon can sometimes desire to change the type of bone anchoring by providing bone anchoring means which exert a compression on the vertebrae around the implant system (i.e. which tend to bring the two adjacent vertebra closer to one another), as for example by bone anchoring means such as screws or anchors the curvature whereof is suited to such an effect (as described in certain documents of the prior art). Moreover, the surgeon may desire (on the same vertebral level of the same patient or on another vertebral level of any patient) that the anchorage not constrain the vertebra in certain directions, or in any direction (including the compression direction). The surgeon is often confronted with problems connected with the selection of the type of attachment, sometimes up to the moment where he proceeds with the surgery, while the prosthesis supplier is confronted with problems connected to cost and stock management while facilitating the surgery for the surgeon.
In this context, it is attractive to propose a solution which can respond to at least a portion of these problems.